In the electrophotography art, there is a need for relatively low fusing temperature toner powders. These toners not only reduce power consumption and copier warm up time, but also increase the useful life of machine components in copiers because of inherent reduced heat spillage from the fuser subsystem. These toners also permit higher speed fusing and reduce problems with paper receivers.
To achieve such results, various approaches have been tried. One approach has been to use linear amorphous polymers with a reduced T.sub.g. However, these polymers result in poor toner keeping characteristics and very little fusing latitude. They also require the use of excessive wicking fluid quantities.
Another approach has been to use crosslinked amorphous polyester toners that utilize a low molecular weight polymer that is crosslinked to achieve fusing latitude as taught in U.S. Pat. No. 3,938,992 and U.S. Reissue Pat. No. 31,072. However, the onset of fusing temperature of these toners is limited by the toner T.sub.g.
Another approach has been to use polyblends such as a blend of an amorphous polyester polymer with a crystalline polyester polymer (as taught in Japanese Laid-Open patent application Kokai No. 65146/1981). However, toners of these blends display poor keeping properties that are evidently caused by the polymers being compatible and behaving as though they constituted a single amorphous polymer with a low T.sub.g.
So far as now known, the prior art approaches have not solved the problem of achieving a low fusing temperature toner powder with good keep and grindability characteristics.